The present invention relates to separating liquids such as petroleum based oils, fuels oils and gasolines from organic and inorganic substances such as water, algae and solids.
Petroleum products are the mainstay of modern industry. Produced as oils they are used in lubrication, as power transfer mediums. In distillate forms such as diesel oil and gasolines they are used in the combustion engine. Because of their importance in every phase of commerce and industry new and improved processes and apparatuses for insuring the quality of petroleum products is vitally important to the industrial sector.
Keeping fuel and other oils free from contamination while storage tanks is a constant challenge for users of petroleum products. Contaminants such as water, salt, rust, and other unwelcome ingredients, even bacteria, invade fuel supply tanks and eventually wreck havoc on an engine or power plant. Managing this problem may take a combination of technologies from centrifuges to an arsenal of water strippers, fuel/water separators, media filtration, mesh screens and chemicals.
Other machinery that benefits from devices that can remove water and other unwanted constituents are those that burn fuel oil such as generators of electricity and oil burners. These machines and burners typically utilize heavy fuel oils generally known by various grades of heating oils and diesel fuels. Marine engines, diesel automobiles and trucks, stationary generators and home oil burners burn differing qualities of fuel oils that can benefit from devices that can remove foreign constituents. Many devices exist for separating fuel from foreign constituents, however, most of these are expensive and rely on mechanical mechanisms and filtration media.
For example, reliable operation internal combustion engines and power generation stations depend on fuels free from contaminants such as water and organic and inorganic solids. Additionally, fuel oil that contains water can freeze fuel lines when temperatures drop below 32 degrees Fahrenheit. Water in oil or fuel also reduces the efficiency of engine performance since at least some energy is dissipated in the process of heating the water and not in combustion as well as the water contributing to the oxidation of metal parts. In many instances, water particulate contribute to engine failure, specifically in engines that utilize injectors to atomize fuel for the combustion chambers. Solid particulate in fuel decreases the efficiency and increases the wear due to frictional forces on internal engine parts. When oil is used as a hydraulic fluid it is important that water and other contaminants be kept to a minimum to reduce wear on components and to maintain the action of the fluid in for its intended purpose.
For ships, it is not uncommon for fuel to remain in storage or service tanks for weeks and for sea water to be carried as ballast in emptied fuel tanks. Bunkering, transport, and long storage periods coupled with the intentional introduction of water, create the perfect environment for water and algae which can clog filters, fuel and injector pumps and start a chain of events which may lead to catastrophic engine failure. In the diesel engine, contamination, whether bacteria, sediment or water, can blow injector tips and cause immediate cylinder scoring.
Selecting the processes that provide treatment of water contaminated fuel and oil supply for modern gas turbine and diesel engines depends on properly assessing competing tradeoffs such as: cost, reliability, performance and importantly, application. Not surprisingly, the process of purification relates strongly to the application, that is, the device or engine technology, together with the grade of oil or fuel it will use and how the fuel is stored.
A best engineered solution for fuel purification considers both cost and performance. Electromechanical centrifuges are a popular solution, performance-wise, for purifying fuels in the light crude oil and heavy fuel oils category because these are only partly refined before delivery to the ship""s tanks. But, distillates do not need the same level of purification, because they are already highly refined. Electromechanical centrifuges may not be the most cost efficient here, because distillates only require that contaminates introduced in transport or during storage, need removal.
Especially for distillate fuels such as No. 2 Diesel, products now exist to eliminate water and sediment by combining centrifugal fuel flow with a sedimenter technology. Unlike their electomechanical centrifugal counterparts, these products contain no filter media or moving parts, except for the fuel pump needed to keep the fuel flowing. These products have the advantages of: low investment cost, low maintenance costs, high reliability, and the ability to employ cross connected links, permitting various real time configurations to suit a ship""s immediate purification needs.
It is well known that impurities such as the presence of an electrolyte or soap in the fluid will cause the water and oil mixture to stabilize. For example, when soap is added to water and oil the result is a stable emulsion that permit the combination to easily be separated from metal and other surfaces, but difficult to separate from each other. But, water and oil can exist in three different states. Free water and oil can remain separate constituents, so called immiscible. In this combination water flows freely in the body of generally greater viscosity oil. The second is the unstable emulsification of oil and water that generally forms droplets of the combination. Here the water/oil forms globules which flow separate from the free water and oil. Thirdly, there is the stable mixture of water and oil.
In the second case, where oil and water are mixed, for example by agitation when oil and water are contained in the same storage tank being used to fill a supply tank, an unstable colloidal dispersion may result. The first colloid is of water in oil and the second oil in water. Coalescing of these colloidal droplets separate into a top layer of oil and a bottom layer of oil. In a tank or sump the water generally settles to the bottom and the oil on the top of the water. And, because oil and water are relatively immiscible, if there is a positive pressure applied during the flow of oil and water the two constituents can be separated into different paths.
The dynamics of the so called emulsified droplets depend to a large degree upon the drag coefficients and flow characteristics of the liquid, ranging from laminar flow to turbulence and defined by the Reynolds number. In defining the values of the energy undertaken by the emulsified particle in a fluid flow we look to the relative value between the emulsified droplet and the bulk fluid.
According to Stokes law, a particle such as an emulsified oil/water particle, falling under the action of gravity will accelerate until the frictional drag of the fluid just balances the gravitational acceleration after which it continues to fall under constant velocity, know as the free settling velocity. To capitalize on the Stokes principle in separating a water particle from an oil particle, the flow of the oil/water mass should remain relatively laminar.
U.S. Pat. No. 4,986,907 describes a diesel fuel refining apparatus that works on a principle of centrifugal forces from a motion the fuel is forced to undergo as it is drawn through the apparatus under the pressure of a pump. In this disclosure claimed centrifugal forces are created when the fuel discharges from an interior pipe and impacts against a pre heated generally flat rectangular metal plate which runs diametrically across a cylindrical container and also substantially longitudinally the length of the interior of the cylinder housing. Due to the preheating of the plate and the angular relationship maintained by the conduit and the plate, the fuel that leaves the pipe and hits the plate is projected to create a turbulence that is claimed to facilitate separation of the fuel components such as water, sulfur, and sulphuric acid. However, turbulence may not be the most efficient mechanism to separate water from oil.
In summary the invention herein disclosed is an apparatus for purifying a liquid, typically a petroleum product, being drawn through the apparatus by the force of a pump, such that the liquid has at least two relatively immiscible constituents with diverse properties, at least one of such property is specific gravity, which comprises a cylindrically shaped container having an input port in fluid communication with an output port, and one or more chambers therein such as an input chamber of decreasing cross section having a discharge nozzle which directs the liquid into the direction of a concave surface, such that due to centrifugal forces acting on differences in specific gravity and viscosity, heavier constituents come to rest in a settling chamber and lighter constituents flow through a first separation chamber and discharge into a second separation chamber whereby the liquid is channeled in a downward position relative to the point the liquid rose in the first separation chamber and then discharges into an output chamber before it is discharged into an output port.
The invention herein is also drawn to a process for purifying a fluid having at least two constituents with diverse properties, where at least one such property is specific gravity, comprising pumping the fluid through a means having an input port in fluid communication with an output port, a means for impinging the fluid into a concave barrier interposed between the input port and the output port, and integral to a settling chamber, such that constituents with the greater specific gravity come to rest in a settling chamber and constituents with the lesser specific gravity flow to the output port.
The apparatus and process herein described, separates water from fuel, fuel oil or oil generally (collectively referred to as petroleum products). It is remarkable in that it contains no moving parts or active filter media, but relies on several scientific and engineering principles to separate water and sediment from petroleum products by utilizing: (1) the relative immiscibility and differences in specific gravity between the water and petroleum products which causes the lighter fuel to precipitate out of the water and thereby prevents water and contaminants from following the precise path of the fuel; (2) centrifugal forces established by virtue of a nozzle the output of which is directed into a cylindrically shaped concave configuration which in turn causes water and contaminants to separate from petroleum products due to their different densities and viscosities; (3) high ratios of surface energy to surface tension, which cause small water particles to form larger droplets on coalescing plates and eventually fall into the settling chamber; (4) weirs to create a stripping action to dislodge water from petroleum products; (5) increasing and decreasing changes in direction, pressure and velocity as the petroleum products pass through various stages within the device to allow the solid contaminants and water to drop out of the petroleum products; and finally (6) differences in viscosity of the various constituents to prevent the water and contaminants from following the precise flow path of the fuel.
The invention herein disclosed separates the contaminates from the petroleum products generally without any added requirement for heat, a heat conducting plate, filtration media or any mechanization.
Under the force of a pump petroleum products and other foreign constituents such as water, algae and sediment, flow into a chamber which conditions the liquid by changing its direction of flow and its velocity and pressure. As the liquid exits the first input chamber, a vortex or rotational flow is created when the liquid is directed against a concave wall of the interior of a cylindrical container and thereafter allowed to circulated in a generally cylindrical volume defined by the settling chamber. The rotation created from the forces of the pump drawing liquid through the system, the liquid being forced into a concave interior surface and of the moving liquid mass (solids and fluids) having differing physical properties such as viscosity and specific gravity. Each constituent will follow a path determined by its individual properties such as its chemical and electronic affinity for the other constituents, viscosity and specific gravity. The liquid or solid under the influence of a centrifugal force as a result of a rotary motion will assume a specific angular acceleration and corresponding angular momentum. Some constituents will be drawn more to the center of rotation and other constituents will circulate further out from the center. During this phase of the operation turbulence is kept to a minimum to better exploit various properties of the liquid under the actions of the dynamic forces employed.
As the dynamic forces due to a pump acting on the liquid diminish to a point where a vortex due to centrifugal forces cannot be sustained, the water, contaminants and oils will generally simply separate in the settling chamber due to gravitational effects. The combined effect of the system is that when flow rates are so low that a sustainable centrifugal force cannot be maintained, separation of the water, contaminants and oil will occur due to gravity and as the centrifugal forces are increased separation will also occur due to the centrifuge effect. In this manner the invention covers the range of flow rates from zero flow to some maximum determined by when the flow is to fast to allow the water and contaminants to assume a damping state and fall into the settling chamber.
Above the region where the cylindrical volume exists is interposed a vertical plate. The vertical plate reduces the tendency toward rotary motion of any liquid that comes in contact with the plate. Since the vertical plate is above the cylindrical volume region, only constituents having a specific gravity above some threshold with respect to constituents having a specific gravity below some threshold will impinge the plate. The liquid constituents that impinge in the vertical plate change direction to conserve momentum under well known laws of physics and are swept in the direction of the fluid current flow provided by the pump.
More specifically, in the present invention, the liquid such as hydraulic oil, diesel oil or gasoline flows through a closed system under pressure supplied by a pump. The liquid and all its extraneous constituents (typically contaminates such as water, sediment, and algae) under the force of the pump enters an orifice of the cylindrical container in a generally parallel attitude with respect to a ground plane or orthogonal to the vertical axis of the cylindrical container.
The orifice is connected to the longitudinal input chamber, which is contained within the larger essentially cylindrical system enclosing chambers and baffles. The longitudinal chamber forces the incoming liquid to change direction through a compound ninety degree angle downward and then a ninety degree angle transverse to the first turn, and then to accelerate under a narrowing of the chamber as it progresses through the chamber towards a distal end where it exits through a constriction or nozzle directed in the general direction of the concave interior surface of the cylindrical chamber. The narrowing of the cross section of the chamber from its proximal end to its distal end results in an increase in the velocity of the petroleum products and its contaminants through the first input chamber.
Upon exiting the nozzle, the fluid is forced into a generally concave surface (the inner surface of a cylindrical chamber can provide such a surface) where the liquid is forced into a spinning or whirlpool-like motion. Here, components of differing specific gravity are deflected at a differing angles due to a combination of centrifugal forces, barriers and properties of the liquid constituents.
The petroleum products or fluid of importance must have a specific gravity lower than the contaminants it filters. For example, fuel oil typically has a specific gravity of between 0.70 and 0.95, whereas water has a specific gravity of 1.0. The heavier specific gravity components do not have the kinetic energy to remain in the current stream and tend to flow towards a lower gravitational potential where a settling chamber at the bottom of the container collects the unwanted constituents. Therefore, water and sediment which are heavier than petroleum products generally will flow away from the concave barrier and settle into the lowest vertical point in the cylindrical chamber referred to as the settling chamber or sump. The lighter petroleum products are swept into the laminar current flow to make its way under pressure of the pump employed through one or more chambers towards the output port.
Petroleum products such as a fuel oil flow into the input port orthogonally with respect to the vertical axis of the cylindrical container. Upon entering the input port and then the longitudinal diverter input chamber fuel impacts a vertical wall or diverter of the first input chamber and is forced to change direction and therefore momentum, into a downward flow through the central passage of the a longitudinal input chamber. As previously indicated, the input chamber has a generally narrowing cross section which forces the fluid to accelerate as it is drawn downward by the force of the pump and gravity. When the fluid containing differing constituents is discharged from the distal end of the input chamber, it is forced to impinge a concave surface integral to a settling chamber, such that constituents with the greater specific gravity come to rest in the settling chamber and constituents with the lesser specific gravity remain in the current stream and proceed through a first separation chamber and eventually flow toward other separation chambers and ultimately the output port.
Through the force of the pump, lesser specific gravity fluid rises in the cylindrical container. The heavier, that is, greater specific gravity components are essentially trapped in the settling chamber by the imposition of a semi-circular half ceiling that contains that portion of the cylindrical container referred to as the settling chamber, where the whirlpool or circular currents occur. A vertical wall separates the first separation chamber and one or more subsequent separation chambers through which the lighter fluid flows to the output port.
In one embodiment a second separating chamber is interposed between the first separation chamber and an output separation chamber. Each passage of fluid from one separation chamber to another forces the fluid to encounter one or more changes in velocity, pressure and direction. These changes are accomplished by weirs or dams or square orifices in which, the fluid carried through the chamber is constrained to flow. The weirs acts to alter the head pressure, the direction and the velocity of the flow, which facilitates separation of components having differing viscosities and other physical properties. The liquid that flows through the first separating chamber exits through a weir at the top of the first separation chamber and into the second separation chamber. It is forced to make a one-hundred and eighty degree change in position and flow downward relative to the vertical axis of the cylindrical. At the distal end of the second separation chamber the liquid exits through a rectangular weir into the output separation chamber where it is then forced in a generally upward flow whereupon it exits the device through an output port.
The second separation chamber is closed on each of its six sides having an input weir and an output weir. The main functions of the enclosure is three-fold: to provide an additional stage of separation for any contaminants that escaped separation in the first separation chamber, to provide large flat surfaces to assist in the coalescing of water, and to incorporate weirs that aid in stripping water and contaminants from the petroleum product. This chamber in cooperation with the sump ceiling and a first separation ceiling isolate the input chamber and first separating chamber from the output separation chamber to prevent any contaminants such as water and sediment resident in the sump from invading the output separation chamber, thus keeping the sump constituents isolated from the clean liquid exiting the system. This feature is especially useful in marine and aircraft applications where the pitch and roll of the craft may become extreme and unless the sump constituents are contained could contaminate the cleaner fluids.
The degree of filtration or separation of water and contaminants from oil generally, diesel fuel oil, and gasolines can be increased by employing multiple stages, that is a multiplicity of input chambers, separating plates, and settling chambers of the aforementioned apparatus or process. That is, where the liquid stream flowing toward the output port is diverted by a second chamber and channeled in a generally downward position relative to the point the fluid rose after a first separation the process of altering direction and changing velocity will further aid in separating oil generally, fuel oil, and gasolines from greater specific gravity constituents. For example, fluid containing diverse constituents discharged from the distal end of the second separation chamber, will cause contaminants to come to rest in the bottom of the second chamber while the lighter fluids flow towards the output chamber. The lighter components are again made to rise in the container before they finally flow out of the output port. This process of adding separation chambers and causing the fluid to change direction and impinge a concave surface or flow past a weir can be repeated as often as necessary to achieve the degree of separation required for a given application.
The invention herein disclosed channels the liquid through one or more separating chambers as previously described resulting in purification of petroleum products. The walls of these channels are typically made from either steel or other material having a high surface energy. The surface energy has the effect of allowing water to be attracted. Therefore the large surface areas essentially coalesce the water that contacts its surface. Smaller water particles accumulate into larger droplets until the mass of the water droplet falls under the influence of gravity.
As a system having one or more of the devices connected in either series or parallel the invention will purify petroleum products by removing free water and most sediment in excess of a given amount. The balance of water and sediment gets removed in the typical primary and secondary filters. This technology has an associated purification/flow rate transfer function which means the larger the size the greater the range of flow rates from nil to some upper limit. Larger units can provide purification at higher fuel flow rates. The tradeoff is size and weight.
Unlike its electomechanical centrifugal counterpart, this invention contains no moving parts, except for the external pump needed to keep the liquid oil or fuel flowing. As a result this device has the advantages of purification with: low investment cost, low maintenance costs and high reliability. When the device is employed in a parallel or series operation it is possible to extend its performance range. In a parallel configuration flow rates can be achieved at any desired level. Connected in series improved filtration degrees can be achieved. Typically in an application that uses more than one device, the redundancy of multiple devices improves system reliability since a purification function often can be performed with less than a full compliment of units operational.
The units can also be utilized to recirculate petroleum products, thereby keeping them free of water and other contaminants. In a recirculation mode separation performance during one pass can be improved with subsequent recirculation. This holds for both water and sediment.
The device offers significant versatility. For example: (1) to transfer and simultaneously purify fuel, from land or marine based fuel supplies to a ship""s or craft""s storage tanks; (2) to recirculate fuel between storage tanks; and (3) to recirculate fuel between the storage tanks and the service or ready day tanks. In its simplest configuration, one or more storage tanks are selected, through one or more of the banks of gate valves controlled either manually or semi automatically through a programmed logic controller or computer, to be pumped through one or more selected devices of the present invention. If a high rate of decontamination is required, then more than one device may be used in parallel operation. In another mode one or more purifying devices are dedicated to purifying fuel in the storage tanks and the balance relegated to transferring fuel from a selected storage tank to a service tank. In yet another mode all of the purifying devices transfer fuel from a selected storage tank to one or both of the service tanks simultaneously. In yet another mode fuel may be transferred and simultaneously purified through the present invention while other modes of transference and purification occurs between or among selected storage or service tanks.
All modes can be switched through corresponding 2-way diaphragm valves operating either manually or semi automatically through a programmed logic controller or computer. This optional control system eliminates the necessity for the operator to manually change modes. In the remote control mode it is possible to control the flow rates during different modes of operation.
Finally, this device may be optionally configured to automatically purge the contamination contents, through a 2-way normally closed direct lift diaphragm valve, when sump sensors are employed to detect that full capacity of the settling chamber or sump is being reached.
An object of the present invention is to separate petroleum based oils and fuels from water and other contaminants.
A second object of the present invention is to increase the isolation between water and contaminants trapped in the sump from contaminating the fluids reaching the output port.
A third object of the present invention is to reduce the cost of fuel purification.
A fourth object is to produce a water fuel separator that has no moving or replaceable filter media.
A fifth object is to produce a water fuel separator that does not require heating to aid in the separation of the water and fuel.